A compound is found to contain 54.5% carbon, 9.1% hydrogen, and 36.4% oxygen. It has a molar mass of 135 g. What is the molecular formula?

C6H12O3

Explanation:

Data obtained from the question include:

C (carbon) = 54.5%

H (hydrogen) = 9.1%

O (oxygen) = 36.4%

To obtain the molecular formula, first, let us obtain the empirical formula. This is illustrated below

C = 54.5%

H = 9.1%

O = 36.4%

Divide by their individual molar mass.

C = 54.5/12 = 4.542

H = 9.1/1 = 9.1

O = 36.4/16 = 2.275

Divide by the smallest

C = 4.542/2.275 = 2

H = 9.1/2.275 = 4

O = 2.275/2.275 = 1

The empirical formula is C2H4O

The molecular formula is simply a multiple of the empirical formula. This is illustrated below:

Molecular formula => [C2H4O]n

The molar mass of the compound as obtained from the question is 135g/mol

Now, with the above information, we can simply calculate the value of n in order to obtain the molecular formula. This is illustrated below:

[C2H4O]n = 135

[(12x2) + (4x1) + 16]n = 135

[24 + 4+ 16]n = 135

44n = 135

Divide both side by the coefficient of n i.e 44

n = 135/44

n = 3

The molecular formula

=> [C2H4O]n

=> [C2H4O]3

=> C6H12O3

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

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